VERY100 Holographic Reflex 4 Reticle Red/Green Dot Sight Scope 21mm Rail Mount (Tan) Total Length:81mm (3.19") Hight:24mm (0.94") Color: TAN.Fits 21mm rail Scope Dimention:36mm x 22mm (1.41" x 0.87" ) Powered by 1 x CR2032 battery (Excluded); Scope Dimention: 36mm x 22mm (1.41" x 0.87")